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*/
1 // vim: filetype=c:tabstop=4:ai:expandtab
2 // SPDX-License-Identifier: ICU
3 // scspell-id: a0c30a33-f62c-11ec-a4e6-80ee73e9b8e7
4 /* ------------------------------------------------------------------- */
5 /* Decimal Context module */
6 /* ------------------------------------------------------------------- */
7 /* Copyright (c) IBM Corporation, 2000, 2009. All rights reserved. */
8 /* */
9 /* This software is made available under the terms of the ICU License. */
10 /* */
11 /* The description and User's Guide ("The decNumber C Library") for */
12 /* this software is called decNumber.pdf. This document is available, */
13 /* together with arithmetic and format specifications, testcases, and */
14 /* Web links, on the General Decimal Arithmetic page. */
15 /* */
16 /* Please send comments, suggestions, and corrections to the author: */
17 /* mfc@uk.ibm.com */
18 /* Mike Cowlishaw, IBM Fellow */
19 /* IBM UK, PO Box 31, Birmingham Road, Warwick CV34 5JL, UK */
20 /* ------------------------------------------------------------------- */
21 /* This module comprises the routines for handling arithmetic */
22 /* context structures. */
23 /* ------------------------------------------------------------------- */
24
25 #include <string.h> // for strcmp
26 #include "decContext.h" // context and base types
27 #include "decNumberLocal.h" // decNumber local types, etc.
28
29 /* compile-time endian tester [assumes sizeof(Int)>1] */
30 static const Int mfcone=1; // constant 1
31 static const Flag *mfctop=(const Flag *)&mfcone; // -> top byte
32 #define LITEND *mfctop // named flag; 1=little-endian
33
34 /* ------------------------------------------------------------------ */
35 /* round-for-reround digits */
36 /* ------------------------------------------------------------------ */
37 const uByte DECSTICKYTAB[10]={1,1,2,3,4,6,6,7,8,9}; /* used if sticky */
38
39 /* ------------------------------------------------------------------ */
40 /* Powers of ten (powers[n]==10**n, 0<=n<=9) */
41 /* ------------------------------------------------------------------ */
42 const uInt DECPOWERS[10]={1, 10, 100, 1000, 10000, 100000, 1000000,
43 10000000, 100000000, 1000000000};
44
45 /* ------------------------------------------------------------------ */
46 /* decContextClearStatus -- clear bits in current status */
47 /* */
48 /* context is the context structure to be queried */
49 /* mask indicates the bits to be cleared (the status bit that */
50 /* corresponds to each 1 bit in the mask is cleared) */
51 /* returns context */
52 /* */
53 /* No error is possible. */
54 /* ------------------------------------------------------------------ */
55 decContext *decContextClearStatus(decContext *context, uInt mask) {
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56 context->status&=~mask;
57 return context;
58 } // decContextClearStatus
59
60 /* ------------------------------------------------------------------ */
61 /* decContextDefault -- initialize a context structure */
62 /* */
63 /* context is the structure to be initialized */
64 /* kind selects the required set of default values, one of: */
65 /* DEC_INIT_BASE -- select ANSI X3-274 defaults */
66 /* DEC_INIT_DECIMAL32 -- select IEEE 754 defaults, 32-bit */
67 /* DEC_INIT_DECIMAL64 -- select IEEE 754 defaults, 64-bit */
68 /* DEC_INIT_DECIMAL128 -- select IEEE 754 defaults, 128-bit */
69 /* For any other value a valid context is returned, but with */
70 /* Invalid_operation set in the status field. */
71 /* returns a context structure with the appropriate initial values. */
72 /* ------------------------------------------------------------------ */
73 decContext * decContextDefault(decContext *context, Int kind) {
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74 // set defaults...
75 context->digits=9; // 9 digits
76 context->emax=DEC_MAX_EMAX; // 9-digit exponents
77 context->emin=DEC_MIN_EMIN; // .. balanced
78 context->round=DEC_ROUND_HALF_UP; // 0.5 rises
79 context->traps=DEC_Errors; // all but informational
80 context->status=0; // cleared
81 context->clamp=0; // no clamping
82 #if DECSUBSET
83 context->extended=0; // cleared
84 #endif
85 switch (kind) {
86 case DEC_INIT_BASE:
87 // [use defaults]
88 break;
89 case DEC_INIT_DECIMAL32:
90 context->digits=7; // digits
91 context->emax=96; // Emax
92 context->emin=-95; // Emin
93 context->round=DEC_ROUND_HALF_EVEN; // 0.5 to nearest even
94 context->traps=0; // no traps set
95 context->clamp=1; // clamp exponents
96 #if DECSUBSET
97 context->extended=1; // set
98 #endif
99 break;
100 case DEC_INIT_DECIMAL64:
101 context->digits=16; // digits
102 context->emax=384; // Emax
103 context->emin=-383; // Emin
104 context->round=DEC_ROUND_HALF_EVEN; // 0.5 to nearest even
105 context->traps=0; // no traps set
106 context->clamp=1; // clamp exponents
107 #if DECSUBSET
108 context->extended=1; // set
109 #endif
110 break;
111 case DEC_INIT_DECIMAL128:
112 context->digits=34; // digits
113 context->emax=6144; // Emax
114 context->emin=-6143; // Emin
115 context->round=DEC_ROUND_HALF_EVEN; // 0.5 to nearest even
116 context->traps=0; // no traps set
117 context->clamp=1; // clamp exponents
118 #if DECSUBSET
119 context->extended=1; // set
120 #endif
121 break;
122
123 default: // invalid Kind
124 // use defaults, and trap
125 (void)decContextSetStatus(context, DEC_Invalid_operation);
126 }
127
128 return context;} // decContextDefault
129
130 /* ------------------------------------------------------------------ */
131 /* decContextGetRounding -- return current rounding mode */
132 /* */
133 /* context is the context structure to be queried */
134 /* returns the rounding mode */
135 /* */
136 /* No error is possible. */
137 /* ------------------------------------------------------------------ */
138 enum rounding decContextGetRounding(decContext *context) {
/* */
139 return context->round;
140 } // decContextGetRounding
141
142 /* ------------------------------------------------------------------ */
143 /* decContextGetStatus -- return current status */
144 /* */
145 /* context is the context structure to be queried */
146 /* returns status */
147 /* */
148 /* No error is possible. */
149 /* ------------------------------------------------------------------ */
150 uInt decContextGetStatus(decContext *context) {
/* */
151 return context->status;
152 } // decContextGetStatus
153
154 /* ------------------------------------------------------------------ */
155 /* decContextRestoreStatus -- restore bits in current status */
156 /* */
157 /* context is the context structure to be updated */
158 /* newstatus is the source for the bits to be restored */
159 /* mask indicates the bits to be restored (the status bit that */
160 /* corresponds to each 1 bit in the mask is set to the value of */
161 /* the corresponding bit in newstatus) */
162 /* returns context */
163 /* */
164 /* No error is possible. */
165 /* ------------------------------------------------------------------ */
166 decContext *decContextRestoreStatus(decContext *context,
/* */
167 uInt newstatus, uInt mask) {
168 context->status&=~mask; // clear the selected bits
169 context->status|=(mask&newstatus); // or in the new bits
170 return context;
171 } // decContextRestoreStatus
172
173 /* ------------------------------------------------------------------ */
174 /* decContextSaveStatus -- save bits in current status */
175 /* */
176 /* context is the context structure to be queried */
177 /* mask indicates the bits to be saved (the status bits that */
178 /* correspond to each 1 bit in the mask are saved) */
179 /* returns the AND of the mask and the current status */
180 /* */
181 /* No error is possible. */
182 /* ------------------------------------------------------------------ */
183 uInt decContextSaveStatus(decContext *context, uInt mask) {
/* */
184 return context->status&mask;
185 } // decContextSaveStatus
186
187 /* ------------------------------------------------------------------ */
188 /* decContextSetRounding -- set current rounding mode */
189 /* */
190 /* context is the context structure to be updated */
191 /* newround is the value which will replace the current mode */
192 /* returns context */
193 /* */
194 /* No error is possible. */
195 /* ------------------------------------------------------------------ */
196 decContext *decContextSetRounding(decContext *context,
/* */
197 enum rounding newround) {
198 context->round=newround;
199 return context;
200 } // decContextSetRounding
201
202 /* ------------------------------------------------------------------ */
203 /* decContextSetStatus -- set status and raise trap if appropriate */
204 /* */
205 /* context is the context structure to be updated */
206 /* status is the DEC_ exception code */
207 /* returns the context structure */
208 /* */
209 /* Control may never return from this routine, if there is a signal */
210 /* handler and it takes a long jump. */
211 /* ------------------------------------------------------------------ */
212 decContext * decContextSetStatus(decContext *context, uInt status) {
/* */
213 context->status|=status;
214 if (status & context->traps) raise(SIGFPE);
215 return context;} // decContextSetStatus
216
217 /* ------------------------------------------------------------------ */
218 /* decContextSetStatusFromString -- set status from a string + trap */
219 /* */
220 /* context is the context structure to be updated */
221 /* string is a string exactly equal to one that might be returned */
222 /* by decContextStatusToString */
223 /* */
224 /* The status bit corresponding to the string is set, and a trap */
225 /* is raised if appropriate. */
226 /* */
227 /* returns the context structure, unless the string is equal to */
228 /* DEC_Condition_MU or is not recognized. In these cases NULL is */
229 /* returned. */
230 /* ------------------------------------------------------------------ */
231 decContext * decContextSetStatusFromString(decContext *context,
/* */
232 const char *string) {
233 if (strcmp(string, DEC_Condition_CS)==0)
234 return decContextSetStatus(context, DEC_Conversion_syntax);
235 if (strcmp(string, DEC_Condition_DZ)==0)
236 return decContextSetStatus(context, DEC_Division_by_zero);
237 if (strcmp(string, DEC_Condition_DI)==0)
238 return decContextSetStatus(context, DEC_Division_impossible);
239 if (strcmp(string, DEC_Condition_DU)==0)
240 return decContextSetStatus(context, DEC_Division_undefined);
241 if (strcmp(string, DEC_Condition_IE)==0)
242 return decContextSetStatus(context, DEC_Inexact);
243 if (strcmp(string, DEC_Condition_IS)==0)
244 return decContextSetStatus(context, DEC_Insufficient_storage);
245 if (strcmp(string, DEC_Condition_IC)==0)
246 return decContextSetStatus(context, DEC_Invalid_context);
247 if (strcmp(string, DEC_Condition_IO)==0)
248 return decContextSetStatus(context, DEC_Invalid_operation);
249 #if DECSUBSET
250 if (strcmp(string, DEC_Condition_LD)==0)
251 return decContextSetStatus(context, DEC_Lost_digits);
252 #endif
253 if (strcmp(string, DEC_Condition_OV)==0)
254 return decContextSetStatus(context, DEC_Overflow);
255 if (strcmp(string, DEC_Condition_PA)==0)
256 return decContextSetStatus(context, DEC_Clamped);
257 if (strcmp(string, DEC_Condition_RO)==0)
258 return decContextSetStatus(context, DEC_Rounded);
259 if (strcmp(string, DEC_Condition_SU)==0)
260 return decContextSetStatus(context, DEC_Subnormal);
261 if (strcmp(string, DEC_Condition_UN)==0)
262 return decContextSetStatus(context, DEC_Underflow);
263 if (strcmp(string, DEC_Condition_ZE)==0)
264 return context;
265 return NULL; // Multiple status, or unknown
266 } // decContextSetStatusFromString
267
268 /* ------------------------------------------------------------------ */
269 /* decContextSetStatusFromStringQuiet -- set status from a string */
270 /* */
271 /* context is the context structure to be updated */
272 /* string is a string exactly equal to one that might be returned */
273 /* by decContextStatusToString */
274 /* */
275 /* The status bit corresponding to the string is set; no trap is */
276 /* raised. */
277 /* */
278 /* returns the context structure, unless the string is equal to */
279 /* DEC_Condition_MU or is not recognized. In these cases NULL is */
280 /* returned. */
281 /* ------------------------------------------------------------------ */
282 decContext * decContextSetStatusFromStringQuiet(decContext *context,
/* */
283 const char *string) {
284 if (strcmp(string, DEC_Condition_CS)==0)
285 return decContextSetStatusQuiet(context, DEC_Conversion_syntax);
286 if (strcmp(string, DEC_Condition_DZ)==0)
287 return decContextSetStatusQuiet(context, DEC_Division_by_zero);
288 if (strcmp(string, DEC_Condition_DI)==0)
289 return decContextSetStatusQuiet(context, DEC_Division_impossible);
290 if (strcmp(string, DEC_Condition_DU)==0)
291 return decContextSetStatusQuiet(context, DEC_Division_undefined);
292 if (strcmp(string, DEC_Condition_IE)==0)
293 return decContextSetStatusQuiet(context, DEC_Inexact);
294 if (strcmp(string, DEC_Condition_IS)==0)
295 return decContextSetStatusQuiet(context, DEC_Insufficient_storage);
296 if (strcmp(string, DEC_Condition_IC)==0)
297 return decContextSetStatusQuiet(context, DEC_Invalid_context);
298 if (strcmp(string, DEC_Condition_IO)==0)
299 return decContextSetStatusQuiet(context, DEC_Invalid_operation);
300 #if DECSUBSET
301 if (strcmp(string, DEC_Condition_LD)==0)
302 return decContextSetStatusQuiet(context, DEC_Lost_digits);
303 #endif
304 if (strcmp(string, DEC_Condition_OV)==0)
305 return decContextSetStatusQuiet(context, DEC_Overflow);
306 if (strcmp(string, DEC_Condition_PA)==0)
307 return decContextSetStatusQuiet(context, DEC_Clamped);
308 if (strcmp(string, DEC_Condition_RO)==0)
309 return decContextSetStatusQuiet(context, DEC_Rounded);
310 if (strcmp(string, DEC_Condition_SU)==0)
311 return decContextSetStatusQuiet(context, DEC_Subnormal);
312 if (strcmp(string, DEC_Condition_UN)==0)
313 return decContextSetStatusQuiet(context, DEC_Underflow);
314 if (strcmp(string, DEC_Condition_ZE)==0)
315 return context;
316 return NULL; // Multiple status, or unknown
317 } // decContextSetStatusFromStringQuiet
318
319 /* ------------------------------------------------------------------ */
320 /* decContextSetStatusQuiet -- set status without trap */
321 /* */
322 /* context is the context structure to be updated */
323 /* status is the DEC_ exception code */
324 /* returns the context structure */
325 /* */
326 /* No error is possible. */
327 /* ------------------------------------------------------------------ */
328 decContext * decContextSetStatusQuiet(decContext *context, uInt status) {
/* */
329 context->status|=status;
330 return context;} // decContextSetStatusQuiet
331
332 /* ------------------------------------------------------------------ */
333 /* decContextStatusToString -- convert status flags to a string */
334 /* */
335 /* context is a context with valid status field */
336 /* */
337 /* returns a constant string describing the condition. If multiple */
338 /* (or no) flags are set, a generic constant message is returned. */
339 /* ------------------------------------------------------------------ */
340 const char *decContextStatusToString(const decContext *context) {
/* */
341 Int status=context->status;
342
343 // test the five IEEE first, as some of the others are ambiguous when
344 // DECEXTFLAG=0
345 if (status==DEC_Invalid_operation ) return DEC_Condition_IO;
346 if (status==DEC_Division_by_zero ) return DEC_Condition_DZ;
347 if (status==DEC_Overflow ) return DEC_Condition_OV;
348 if (status==DEC_Underflow ) return DEC_Condition_UN;
349 if (status==DEC_Inexact ) return DEC_Condition_IE;
350
351 if (status==DEC_Division_impossible ) return DEC_Condition_DI;
352 if (status==DEC_Division_undefined ) return DEC_Condition_DU;
353 if (status==DEC_Rounded ) return DEC_Condition_RO;
354 if (status==DEC_Clamped ) return DEC_Condition_PA;
355 if (status==DEC_Subnormal ) return DEC_Condition_SU;
356 if (status==DEC_Conversion_syntax ) return DEC_Condition_CS;
357 if (status==DEC_Insufficient_storage ) return DEC_Condition_IS;
358 if (status==DEC_Invalid_context ) return DEC_Condition_IC;
359 #if DECSUBSET
360 if (status==DEC_Lost_digits ) return DEC_Condition_LD;
361 #endif
362 if (status==0 ) return DEC_Condition_ZE;
363 return DEC_Condition_MU; // Multiple errors
364 } // decContextStatusToString
365
366 /* ------------------------------------------------------------------ */
367 /* decContextTestEndian -- test whether DECLITEND is set correctly */
368 /* */
369 /* quiet is 1 to suppress message; 0 otherwise */
370 /* returns 0 if DECLITEND is correct */
371 /* 1 if DECLITEND is incorrect and should be 1 */
372 /* -1 if DECLITEND is incorrect and should be 0 */
373 /* */
374 /* A message is displayed if the return value is not 0 and quiet==0. */
375 /* */
376 /* No error is possible. */
377 /* ------------------------------------------------------------------ */
378 Int decContextTestEndian(void) {
/* */
379 Int res=0; // optimist
380 uInt dle=(uInt)DECLITEND; // unsign
381 /* cppcheck-suppress knownConditionTrueFalse */
382 if (dle>1) dle=1; //-V547
383
384 if (LITEND!=DECLITEND) {
385 res=(Int)LITEND-dle;
386 }
387 return res;
388 } // decContextTestEndian
389
390 /* ------------------------------------------------------------------ */
391 /* decContextTestSavedStatus -- test bits in saved status */
392 /* */
393 /* oldstatus is the status word to be tested */
394 /* mask indicates the bits to be tested (the oldstatus bits that */
395 /* correspond to each 1 bit in the mask are tested) */
396 /* returns 1 if any of the tested bits are 1, or 0 otherwise */
397 /* */
398 /* No error is possible. */
399 /* ------------------------------------------------------------------ */
400 uInt decContextTestSavedStatus(uInt oldstatus, uInt mask) {
/* */
401 return (oldstatus&mask)!=0;
402 } // decContextTestSavedStatus
403
404 /* ------------------------------------------------------------------ */
405 /* decContextTestStatus -- test bits in current status */
406 /* */
407 /* context is the context structure to be updated */
408 /* mask indicates the bits to be tested (the status bits that */
409 /* correspond to each 1 bit in the mask are tested) */
410 /* returns 1 if any of the tested bits are 1, or 0 otherwise */
411 /* */
412 /* No error is possible. */
413 /* ------------------------------------------------------------------ */
414 uInt decContextTestStatus(decContext *context, uInt mask) {
/* */
415 return (context->status&mask)!=0;
416 } // decContextTestStatus
417
418 /* ------------------------------------------------------------------ */
419 /* decContextZeroStatus -- clear all status bits */
420 /* */
421 /* context is the context structure to be updated */
422 /* returns context */
423 /* */
424 /* No error is possible. */
425 /* ------------------------------------------------------------------ */
426 decContext *decContextZeroStatus(decContext *context) {
/* ![[last]](../icons/n_last.png)
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427 context->status=0;
428 return context;
429 } // decContextZeroStatus
430
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*/